This invention is an improvement in the methods of setting or resetting electrical structures, while simultaneously improving the electrical grounding of the same. line protection of poles or encapsulation of pole treatment chemicals and enhancement of the strength to density ratio, of rigid foam polyurethane resins formed in-situ. The improvement resides in the use of compositions having electrical conductivity. The resulting electrical contact surface area of the pole to the earth is greatly enhanced relative to conventional grounding techniques.
The present invention is an improvement in the technology disclosed in U.S. Pat. No. 3,968,657 to Hannay, U.S. Pat. No. 5,466,094 to Kirby et al., U.S. Pat. No. 3,564,859 to Goodman, U.S. Pat. No. 3,403,520 to Goodman, and U.S. Pat. No. 4,966,497 to Kirby which describe related methods for resetting poles with foam plastic. It is also an improvement over published U.S. application No. 2003/0210959 A1 of Hannay et al, which discusses improved grounding using foam polyurethane compositions. The entire disclosures of U.S. Pat. Nos. 3,968,657, 3,564,859, 3,403,520, 4,966,497, 5,466,094, and published U.S. application No. 2003/0210959 A1 are incorporated by reference as though fully set out herein.
In brief, U.S. Pat. No. 3,403,520 describes a method of setting pole forms in the ground by making a hole which is only slightly larger than the butt of the pole to be placed in the hole, placing the pole in the hole in the desired position, partially filling the hole with a reactive component mixture with a synthetic resin and a blowing agent and permitting the reaction to complete so as to expand the resinous foam into all the space between the pole and the sides of the hole. The expanded resinous foam adheres to and seals the surface of the embedded section of the pole protecting it from moisture, chemicals and rodents and sets the pole in the hole. The expanding resinous foam fills all the voids, surfaces, crevices and notches in the sides and bottom of the hole.
U.S. Pat. No. 3,564,859 describes a procedure for straightening and refilling the hole. It utilizes the same method as U.S. Pat. No. 3,403,520 for producing foam and for filling voids resulting when an existing installed pole has been realigned after it has been canted or tilted.
U.S. Pat. No. 3,968,657 was an improvement upon the in-situ reaction chemistry used to prepare the backfill material. The '657 patent disclosed the addition of a non-volatile water-immiscible material to the mixture so that properties of the resultant product are not affected excessively in the presence of groundwater. A further improvement in the backfill-forming chemistry was described in U.S. Pat. No. 4,966,497. The '497 patent describes a procedure that is an improvement on the above methods because halogenated hydrocarbon blowing agents, more particularly chlorofluorocarbons, are not required. Further, the composition decreased the cost per unit of the polyurethane foam.
U.S. Pat. No. 5,466,094 represented another improvement pole setting or resetting compositions and methods. In the '094 patent, the polyurethane forming chemistry was modified by stabilizing the highly reactive isocyanate component by pre-reaction to form a prepolymer. Published U.S. application No. 2003/0210959 A1 describes how resetting pole compositions can be used to enhance grounding generally. However, given the proliferation of sensitive electronic circuitry of modem devices such as the personal computer, there remains a need to efficiently ground electrical structures in such a way that optimally removes harmonic components which lead to harmonic distortion.
All of the aforementioned patents are devoid of any teaching which describes a backfill composition or method which simultaneously sets or resets an electrical structure and aids in the electrical grounding of the structure. A good ground connection effectively directs the excessive current from a lightening strike to the ground. Proper grounding also helps to insure the quality of the power being transmitted by helping to eliminate or minimize voltage spikes and interference such as RF signals from adversely affecting sensitive electronic equipment.
The present invention simultaneously improves the stability and grounding of modem electrical structures and transmission lines. Electrical systems in the United States use the crust of the earth as part of the return conductor. The grounded, system neutral protects the phase conductors from excessive amperage and voltage as well as to help balance phase voltage and harmonics. Continuously grounded “static” shield wire's purpose is to get the excessive current of a lightening strike into the ground as soon as possible to avoid damage to the shielding conductors, and the buildup of excessive unbalanced voltage on the phases. Good grounding is particularly important today with the sophisticated electronic equipment currently widespread. Additionally, good grounding helps to minimize service interruptions. The need for good backfill materials to set and reset electrical line structures has been known for quite some time and good progress has been made in this area. By making any of the currently used backfill materials conductive and optimally placing such materials, the surface area “connected” to the earth can be greatly enhanced, and harmonic distortion can be significantly reduced.
For instance, the typical method of connecting to the earth is a ⅝ths inch×10 foot ground rod driven into the earth. This method has a surface area of 235 in2. A 10 inch×10 inch copper plate has a surface area of 100 in2. A butt wrap ground of No. 6 copper wire, 20 feet long, wrapped around the pole will give a surface area of 75 in2. This is compared to the surface area of a backfill, which is an approximately 20 inch diameter hole, 6 feet deep, giving a surface area in contact with the earth of up to 4500 in2 which is 19 and 60 times bigger respectively. Therefore, the electrical contact with the ground is increased. This is important in the areas of poor soil conductivity. As was discussed above, U.S. Pat. No. 4,966,497 teaches the use of using a modified urethane as a pole backfill material. By expanding the physical properties of this backfill material to include electrically conductive capabilities, the surface area and abilities of the grounding are vastly improved to include electrical ground in addition to physical grounding.
Electrical losses in transmission and distribution are proportional to the square of the current multiplied by the impedance. For this reason, it is advantageous for electrical transmission lines to operate at a high voltage, low current mode to minimize losses. Given a constant impedance, current and voltage are directly proportional; a decrease in one is compensated by a proportional increase in the other. Hence, transmission is optimally performed in a high voltage, low current mode. Prior to use, however, this must be transformed to a low voltage source as almost all equipment would be destroyed by the high voltages used in transmission. Proper grounding of the electrical transmission at optimal locations, can be used to efficiently reduce and sometimes eliminate harmonic components which lead to harmonic distortion. Grounding is an important “safety valve” of an electrical system, protecting both the system and persons working on the system. Proper grounding is important for a number of reasons. All electrical equipment requires grounding because of possible short circuits within the system. Electrical sensors, such as relays require a reference, which is oftentimes ground. Harmonics created by semiconductor equipment and unbalanced loads depend upon good ground to stabilize the system. The standard AC system in the U.S. operates at 60 cycles/second (Hz). Harmonics are additional cycles superimposed on the 60 Hz cycle curve. The total load comprises the basic sine wave of the expected system load plus the harmonics generated, resulting in a much larger total than the expected load. Harmonics are oftentimes caused by unbalanced loads; such as produced by single phase motors, temporary faults on the line or equipment and by the use of semiconductors, etc. Harmonics can be reduced substantially by a strong ground as close to the load as possible.